Fluidic fuel injection device having air modulation

ABSTRACT

Means for regulating the air-fuel mixture ratio in a fuel delivery system. The present invention departs from other known fuel delivery systems in that the air flow is scheduled as a function of the operator&#39;&#39;s selected fuel flow. In conventional systems the fuel flow is scheduled as a function of the operator&#39;&#39;s selected air flow. Fluidic technology is utilized in a preferred embodiment for the sensing, computation, and actuation of the required variables.

United States Patent [191 Woods Nov. 13, 1973 FLUIDIC FUEL INJECTIONDEVICE [56] References Cited HAVING AIR MODULATION UNITED STATES PATENTS[75] Inventor: Robert L. Woods, Kensington, Md. 2,330,650 9/1943 Weiche261/50 [73] Assignee: The United States of America as represented by thesecretary of the Primary Examzner-WendellE. Burns Army, Washington DC.Attorney-Harry M. Saragovnz et al.

[22] Filed: May 15, 1972 57 T CT [2]] Appl. No.: 253,069 Means forregulating the air-fuel mixture ratio in a fuel delivery system. Thepresent invention departs from other known fuel delivery systems in thatthe air [52] g? gg 32 7 2 flow is scheduled as a function of theoperators se- 261/DIG lected fuel flow. In conventional systems the fuelflow is scheduled as a function of the operator's selected a embodimentfor the sensing, computation, and actua- 261/51 123/119 32 B S'SZ tionof the required variables.

9 Claims, 5 Drawing Figures PAIENIEDrmv 13 1915 3 7 7 l 5 U4 SHEET 10F 22 \o OPERATOR FUEL FLOW L 1 SPEED CONTROL THROTTLE FNGNE TORQUE.

5 8 Edi F =MEA5UF2ED FUEL NR/FUEL FLOW RATE SCHEDULE Ad DESHZED MR JFLOW RATE 4 5 AQ AcTuAL AHZ FLOW RATE E ERROR PRES R REGULATO 56PATENTEHHM 13 1915 3.771; 504

'1 sum 2 OF 2 PRRESSURE EGUUX 1 POINTS FLUIDIC FUEL INJECTION DEVICEHAVING AIR MODULATION RIGHTS OF GOVERNMENT The invention describedherein may be manufactured, used, and licensed by or for the UnitedStates Government for governmental purposes without the payment to me ofany royalty thereon.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to fuel delivery systems, and more particularly, to systems forregulating the air-fuel mixture ratios for internal combustion engines.

2. Description of the Prior Art There has long been interest in fuelcontrol systems for spark ignition internal combustion engines. Systemsto improve economy, boost power and performance, or to decrease costhave been investigated in large numbers. The present emphasis is towardreduced exhaust emissions. Very complicated and/or precise fuelmanagement systems are being developed in the hope of finding anddeveloping means for finer scheduling of air-fuel mixtures to reduceemissions. As a result, economy and power considerations for lowemissions are suffering since in conventional systems, these aregenerally nonconcomitant requirements.

With the advent of fluidic technology, engineers saw the possibilitiesof utilizing fluidic amplifiers in the sensing of engine operatingconditions and the metering of air-fuel mixture requirements. See, forexample, the following U. S. Pats. Nos.: 3,477,699; 3,388,898;3,386,709; 3,406,951; 3,587,543; 3,386,710; 3,389,894; 3,463,176;3,556,063. I acknowledge the advantages of the foregoing devices in thereduction of the number of moving parts and increased reliability andbetter fuel management; however, they all have the inherent disadvantageattendant existing carburetion systems in which the fuel flow isscheduled as a function of the operators selected air flow.

Accordingly, it is a primary object of the present invention to providea fuel management system for an internal combustion engine in which fuelflow is controlled directly by the operator whereby optimum air flow isscheduled and controlled as the function of the selected fuel flow.

Another object of the present invention is to provide a fuel managementdevice having the simplicity of a carburetor combined with theoperational capabilities of complex fuel injection systems.

A further object is to provide a fuel management system which deliverslow emissions normally associated with precise scheduling of very leaneconomical mixtures but still having the capabilities of providing therich mixtures required for maximum performance with no additionalcircuitry.

Another object is to provide a fuel management system that is applicableto either continuous or pulsed fuel injection systems.

A still additional object of the present invention is to provide a fuelmanagement system in which the required control variables to be sensedare all available within the device thus requiring no additionalcircuitry.

Additional object of the present invention is to provide a fuelinjection device that utilizes air modulation and has thecharacteristics of simplicity of design, no

moving parts, inexpensive to manufacture, and high reliability.

SUMMARY OF THE INVENTION Briefly, in accordance with the invention,apparatus for regulating the air-fuel mixture ratios in fuel deliverysystems for an internal combustion engine is provided which comprisesmeans for selecting a fuel flow rate under the direct control of theoperator and means for controlling the desired air flow rate as afunction of the fuel flow rate. Disclosed are two embodiments of thefuel delivery system: one which utilizes continuous fuel injection andthe other which utilizes a pulsed fuel injection system. The embodimentsare presented in the fluidic context, although it is understood that thesystem as described below can be implemented utilizing a variety ofarts, such as mechanically, electronically, hydraulically, orfluidically.

BRIEF DESCRIPTION OF DRAWING The specific nature of the invention aswell as other objects, aspects, uses, and advantages thereof willclearly appear from the following description and from the accompanyingdrawings, in which:

FIG. 1 illustrates in block diagram form the fuel management systemwhich is the heart of the present invention;

FIG. 2 illustrates a schematic representation of a preferred embodimentof the present invention;

FIG. 3 presents another preferred embodiment of the present invention;and

FIGS. 4 and 5 are graphs which are helpful in understanding theprinciples of operation of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A spark ignition internalcombustion engine requires the delivery of air and fuel in properproportions in order to support efficient combustion. The optimumair-fuel mixture ratio varies somewhat with operation; however, the twomust be accurately coordinated for optimum engine operation.

The basic fuel management concept of the present invention isillustrated in FIG. 1. In FIG. 1, the fuel flow 1 is the independentinput under the direct control of the operator via the control means 12to the engine 2. The controlled variable of the system of the presentinvention is the optimum air flow rate scheduled as a function of theoperators selected fuel flow rate. For each value of fuel flow ratethere is a corresponding optimum value for the air flow rate. This isillustrated by means of the graph in FIG. 4 wherein it is seen that fora given fuel flow, F, there is a single value for the optimum air-fuelratio A/F regardless of engine speed. The dashed line of FIG. 4represents the stoichiometric ratio. This optimum or desired air flowrate, A,,, is the output from a function generator 3 which schedules thedesired air flow A as a function of the fuel flow F as shown by thecurve of FIG. 5. Also measured from engine 2 along the conduit 5 is theactual air flow rate A The desired air flow rate from conduit 4 and theactual existing air flow rate along conduit 5 are compared in a summingjunction 6. The two should coincide; if they do not, an error signal isgenerated along conduit 7 that indicates the difference between thedesired and the actual air flow rates. This error signal E is used toactuate the throttle of the engine along conduit 9 until the error inthe actual air flow is reduced to zero. An integrator 8 maintains theactuation signal required for zero error. With the proper sechduling ofair flow and fuel flow, the engine 2 can produce an optimum speed 10depending on the loading torque 11.

The above described system illustrated in FIG. 1 can be implementedutilizing a variety of arts including mechanical, electronic, fluidpower, or fluidic. Components to implement each of the functions in theblock diagram of FIG. 1 are well known to designers knowledgable in thedisciplines mentioned above. The following description of a preferredembodiment is directed towards a fluidic implementation since it appearsto be the least complicated of the foregoing.

The fluidic embodiments can be realized in either continuous or pulsedfuel injection systems. In both cases the fuel consumption rate iscontrolled by the operator and the air consumption rate is controlled bythe fluidic control'circuitry. Fluidic control circuitry can beidentical for the two types of systems. Another common feature of thetwo systems is fuel limiting sensitive to engine speed. The maximum fuelflow which an engine can consume without flooding is directlyproportional to its speed. This maximum fuel flow occurrs at fullthrottle. A device such as a mechanical fuel pump driven by enginespeedmay be necessary to produce a maximum fuel flow capability as a functionof engine speed. The operator can select any fractional part of themaximum fuel rate obtainable at a given speed by means of a fuelconsumption modulator. By limiting fuel flow in this manner, theoperator can select any fuel flow rate he desires; the speed sensitivelimiting will merely prevent him from selecting a fuel flow large enoughto flood the engine. The location of fuel injection, the modulation andthe measurement of fuel consumption differs for the two systems.

The fluidic circuit for the continuous fuel injection systems is shownin FIG. 2. In operation, fuel from a reservoir storage tank 21 ispressurized by an electric fuel pump 22 which provides a power sourcefor the fluidic circuitry and the fuel injection nozzle 27. A pressureregulator 23 maintains a constant fuel pressure along conduit 24 fromfuel pump 22 for the fluidic control circuitry. A mechanical fuel pump25 driven by the engine limits the maximum fuel consumption which can bedelivered. A variable fluid resistor 26, which is controlled by theoperator via e.g. a foot pedal, is used to modulate the fuel consumptionrate. The operators selected fuel flow rate is then directed alongconduit 41 to a mixing device 39 which finely atomizes the fuel andmixes it with the intake air through opening 45. The fuel can beinjected in a variety of places and manners. The fuel injection nozzle27 provides a high velocity point for fuel injection both for idling andfor high engine speeds. Conduit 41 ends in a flexible portion 40 toprovide freedom of movement for nozzle 27 which is rigidly attached tothrottle 42 at point 43. Injection at the orifice 33 or from the walladjacent to throttle 42 are other alternatives to the one shown.

The fuel flow directed toward the engine is passed through a measuringfluid resistor 28. The pressure drop across resistor 28 is indicative ofthe fuel flow rate. This measured fuel flow signal is the input 29 to aproportional fluid amplifier 30. This fluid amplifier serves as afunction generator and is specially designed to have input-outputcharacteristics corresponding to the optimum air-fuel mixture schedule.The graphical representation of the input-output characteristics isshown in FIG. 5 wherein the fuel flow F is plotted as the input to fluidamplifier 30 and the output is designed to follow the solid curve shown.The design of a suitable amplifier is well within the purview of oneordinarily skilled in the fluidic art. The output of amplifier 30 is apressure signal along conduit 31 indicating the desired air flow rate Aas a function of the measured fuel flow rate F.

The actual air flow rate to the engine A,, is indicated along conduit 32by the pressure drop across a measuring orifice 33 located in the mainair intake stream 45 of mixing device 39. A variable fluid resistor 34is employed to allow adjustment in the overall air-fuel ratio. Thedesired air flow rate along conduit31 and the actual air flow rate alongconduit 32 are compared in a proportional fluidic summing amplifier 35.Fluidic summing amplifier 35 is specially designed to permit theoperation of a gasoline power jet deflected by a pneumatic vacuumcontrol jet without entrainment of gasoline in the control line. Summingamplifier 35 is designed such that if the desired and indicated airflows coincide, no error signal E will be produced. If these air flowsignals are not the same value, an error signal will be generated alongoutput 36 to actuate a fluid power actuator 37 that adjusts the throttleposition by means of connection 38 and thereby adjusts the air flow inmixing device 39 until the error is reduced to zero. The actuator 37provides the function of integration to maintain the throttle positionrequired for zero error.

The fluidic control circuit for the pulsed fuel injection system isshown in FIG. 3. In this system a pulsed signal is generated by eithermechanical, electronic or fluid means. An electrical circuit is shown inFIG. 3 wherein the signal from the points in the engine is passed viawire 69 to a one shot multivibrator 70. The one shot produces a pulse ofspecified duration each time it is triggered by the signal from thepoints. The operators control of the pulse width is represented by thevariable resistance 71. The pulse output of one shot is fed to solenoid68 which produces fuel pulses in accordance with the one shot 70. Thefrequency of fuel pulses so produced is directly proportional to theengine speed. This frequency and the pulse width or amplitude, or both,determines the fuel consumption. In the system of the present invention,it is convenient to consider only the pulse width as being variable. Theamplitude may be maintained at a constant pressure, and the pulsefrequency as determined by the engine speed in conjunction with thepulse width or duration will provide the desired fuel limiting.

In the operation the circuit of FIG. 3, the pulsed fuel signal alongconduit 51 is smoothed to a continuous (DC) value by a fluidicresistive-capacitive filter. A fluid resistor 52 and a fluid capacitor53 comprise the fluidic filter which is set to filter the maximum ACfrequency to a usable DC signal. The filtered signal along line '54 isdirectly related to the engine fuel consumption. Once the fuelconsumption signal is obtained, the operation of the air control circuitis identical to that of the continuous fuel injection system describedin FIG. 2 above. That is to say, the measured fuel consumption signal isthe input 54 to a specially fabricated proportional fluidic amplifier 55which has inputoutput characteristics in the shape of the desiredairfuel schedule. The output of amplifier 55 is a pressure signal alongline 56 indicative of the desired air flow rate. The actual air flowrate along line 57 is indicated by the pressure drop across an orifice58 located in the main air stream 66. A variable fluid resistor 59 isused to adjust the overall air-fuel ratio desired. The desired 56 andactual 57 air flow signals are compared in a fluidic summing junction 60which has been specially designed to operate with a gasoline power jetand a pneumatic vacuum control signal without entrainment of gasoline inthe control port. The output of summing junction 60 is an error signalthrough conduit 61 indicating the difference between the desired andactual air flow. The error signal is used to move a fluid power actuator62 which in turn actuates the position of shaft 63 and throttle 65 whichcontrols air consumption through port 67. The actuation continues unitlthe error is reduced to zero.

It is seen by the foregoing that l have provided a fuel injection devicethat utilizes a completely novel and unique air modulation technique.This philosophy of mixture scheduling-permits the scheduling of leaneconomical or optimum emission mixture ratios for normal operation belowfull throttle. As fuel and loading are increased, the full throttlelimit is reached in which the throttle 65 is fully opened and no moreair can be naturally aspirated. With this system, the operator can thenincrease fuel flow if he so desires. This action will signal the controlsystem to increase air flow; however, at full throttle no more air canbe aspirated at a given speed. The net effect is that a rich mixture isdelivered to the engine. Although this operation is not at optimumeconomy or emissions, more power can be obtained with the richermixture. Thus, the lean mixtures for economy or emissions and the richmixtures for power are both inherently delivered by this device withoutany changes in setting or progressive stages such as in a four barrelcarburetor. Other fuel systems without progressive staging must be seteither lean for economy or rich for power but not both.

The device of the present invention inherently provides accelerationenrichment. Since throttle actuation lags a sudden changes in fuel flow,the delivered mixture ratio is temporarily enriched for acceleration andleaned for deceleration. The actuation dynamics can be sized provide theproper lag. This eliminates the additional accelerator pump circuitryrequired in most carburetors. Most conventional systems do not haveprovisions for deceleration leaning, also inherently provided by thedevice of the present invention.

FIG. 5 makes it clear that the optimum air-fuel function has the shapeof the input-output characteristics of atypical fluidic device. Thisallows simple and accurate mixture scheduling. Additionaly, coldenrichment as a function of engine water temperature can be provided bya temperature sensing resistance in the cooling systems with no movingparts, whereas in conventional carburetors a moving part choke isnecessary which is sensitive to exhaust temperatures. Compensation forenvironmental changes can easily be added. As an added feature, therequired control variables to be sensed are all available within thedevice of the present invention. All signals exist as fluidic signals sothat the interfaces between fluid signals and mechanical or electricalsignals required in most systems is avoided. The existing fuel pressurecan be used in the fluidic circuit for computation and actuation,eliminating the need for a separate power source. The device of thepresent invention provides simplicity in design, minimal moving parts,high reliability and is inexpensive to produce.

1 wish it to be understood that I do not desire to be limited to theexact details of the construction shown and described, for obviousmodifications will occur to a person skilled in the art.

I claim:

1. Apparatus for regulating the air fuel mixture ratios in a fueldelivery system or an internal combustion engine, comprising:

a. Means for selecting a fuel flow rate to said engine, said selectingmeans under the direct control of the operator of said engine;

b. means for scheduling the desired air flow rate as a function of saidfuel flow rate;

c. means for comparing said desired air flow rate with the actual airflow rate and for issuing the first signal indicative of the differencetherebetween; and

d. means for adjusting said actual air flow rate in re sponse to saidsignal to correspond to said desired air flow rate.

2. The invention according to claim 1 wherein said scheduling means andsaid comparing means have no moving parts.

3. The invention according to claim 2 wherein said scheduling meanscomprise a fluidic amplifier whose input-output characteristicscorrespond to the desired air-fuel mixture ratio.

4. The invention according to calim 3 further comprising means formixing said fuel flow with said desired air flow.

5. The invention according to claim 4 wherein said mixing meanscomprises a. means for measuring the actual air flow rate to said engineand for delivering a second signal indicative thereof to said comparingmeans and b. a throttle for controlling the air flow rate to saidengine.

6. The invention according to claim 5 wherein said comparing meanscomprises a fluidic summing ampli 7. The invention according to claim 6wherein said adjusting means comprises a fluid power actuator that isconnected to said throttle.

8. The invention according to claim 7 wherein said selecting meanscomprises a variable fluid resitrictor that provide a continuous flow offuelto said engine.

9. The invention according to claim 7 wherein said selecting meanscomprises means for generating a pulsed fuel signal to said engine.

1. Apparatus for regulating the air fuel mixture ratios in a fueldelivery system or an internal combustion engine, comprising: a. Meansfor selecting a fuel flow rate to said engine, said selecting meansunder the direct control of the operator of said engine; b. means forscheduling the desired air flow rate as a function of said fuel flowrate; c. means for comparing said desired air flow rate with the actualair flow rate and for issuing the first signal indicative of thedifference therebetween; and d. means for adjusting said actual air flowrate in response to said signal to correspond to said desired air flowrate.
 2. The invention according to claim 1 wherein said schedulingmeans and said comparing means have no moving parts.
 3. The inventionaccording to claim 2 wherein said scheduling means comprise a fluidicamplifier whose input-output characteristics correspond to the desiredair-fuel mixture ratio.
 4. The invention according to calim 3 furthercomprising means for mixing said fuel flow with said desired air flow.5. The invention according to claim 4 wherein said mixing meanscomprises a. means for measuring the actual air flow rate to said engineand for delivering a second signal indicative thereof to said comparingmeans and b. a throttle for controlling the air flow rate to saidengine.
 6. The invention According to claim 5 wherein said comparingmeans comprises a fluidic summing amplifier.
 7. The invention accordingto claim 6 wherein said adjusting means comprises a fluid power actuatorthat is connected to said throttle.
 8. The invention according to claim7 wherein said selecting means comprises a variable fluid resitrictorthat provide a continuous flow of fuel to said engine.
 9. The inventionaccording to claim 7 wherein said selecting means comprises means forgenerating a pulsed fuel signal to said engine.